Enhancement of aldose reductase activity by modification of an active site lysine: A possible mechanism for in vivo activation

1990 ◽  
Vol 30 ◽  
pp. 195-213 ◽  
Author(s):  
T.Geoffrey Flynn ◽  
Christina Lyons ◽  
David J. Hyndman
Keyword(s):  
Aldose Reductase ◽  
Active Site ◽  
Reductase Activity

Factors affecting the ratio of different organic osmolytes in renal medullary cells

1990 ◽  
Vol 259 (5) ◽  
pp. F847-F858 ◽  
Author(s):  
T. Moriyama ◽  
A. Garcia-Perez ◽  
M. B. Burg
Keyword(s):  
Tissue Culture ◽  
Aldose Reductase ◽  
Glucose Concentration ◽  
Reductase Activity ◽  
Renal Medulla ◽  
Organic Osmolytes ◽  
Factors Affecting ◽  
High Concentrations ◽  
Medullary Cells

Renal medullary cells contain high concentrations of sorbitol, inositol, glycerophosphorylcholine (GPC), and betaine, which balance the variably high osmolality of extracellular NaCl. We found that PAP-HT25 (rabbit renal medullary) cells in tissue culture increase their content of all four when medium osmolality is increased by adding NaCl and urea. However, this requires that betaine be added to medium in addition to customary constituents. Some factors affecting the mix of organic osmolytes in these cells during hypertonicity are as follows. 1) Urea in medium increases cell GPC and tends to decrease others, particularly betaine. 2) With small increases in medium NaCl, intracellular inositol is highest, whereas sorbitol predominates with large NaCl increases. 3) When osmolality is suddenly decreased, these four organic osmolytes exit rapidly from cells, but in differing relative amounts (betaine much greater than sorbitol greater than inositol much greater than GPC). 4) Altering cell betaine levels (by varying betaine in medium) causes reciprocal changes in cell sorbitol (by affecting aldose reductase activity) and vice versa, whereas inositol and GPC are less affected. 5) Raising medium glucose concentration (from which sorbitol is synthesized) increases cell sorbitol and decreases cell inositol and betaine. 6) Decreasing the amount of GPC in cells (by removing choline from medium) causes small changes in betaine and sorbitol, but not in inositol. Changing the amount of inositol does not affect the others. Similar interrelations may operate in vivo to vary the mix of organic osmolytes in renal medulla.

Inhibitory Effects ofZingiber officinaleRoscoe Derived Components on Aldose Reductase Activity in Vitro and in Vivo

2006 ◽  
Vol 54 (18) ◽  
pp. 6640-6644 ◽  
Author(s):  
Atsushi Kato ◽  
Yasuko Higuchi ◽  
Hirozo Goto ◽  
Haruhisa Kizu ◽  
Tadashi Okamoto ◽  
...  
Keyword(s):  
Aldose Reductase ◽  
Reductase Activity ◽  
Inhibitory Effects

scholarly journals Effect of Berberine on Glycation, Aldose Reductase Activity, and Oxidative Stress in the Lenses of Streptozotocin-Induced Diabetic Rats In Vivo—A Preliminary Study

2020 ◽  
Vol 21 (12) ◽  
pp. 4278
Author(s):  
Maria Zych ◽  
Weronika Wojnar ◽  
Magdalena Kielanowska ◽  
Joanna Folwarczna ◽  
Ilona Kaczmarczyk-Sedlak
Keyword(s):  
Oxidative Stress ◽  
Aldose Reductase ◽  
Soluble Protein ◽  
Reductase Activity ◽  
Thiobarbituric Acid ◽  
Isoquinoline Alkaloid ◽  
Diabetic Rats ◽  
Protein Sulfhydryl Groups ◽  
And Oxidative Stress

Diabetes mellitus affects the eye lens, leading to cataract formation by glycation, osmotic stress, and oxidative stress. Berberine, an isoquinoline alkaloid, is a natural compound that has been reported to counteract all these pathological processes in various tissues and organs. The goal of this study was to evaluate whether berberine administered at a dose of 50 mg/kg by oral gavage for 28 days to rats with streptozotocin-induced diabetes reveals such effects on the biochemical parameters in the lenses. For this purpose, the following lenticular parameters were studied: concentrations of soluble protein, non-protein sulfhydryl groups (NPSH), advanced oxidation protein products (AOPP), advanced glycation end-products (AGEs), thiobarbituric acid reactive substances (TBARS), and activities of aldose reductase (AR), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Diabetes induced unfavorable changes in the majority of the examined parameters. The administration of berberine resulted in an increased soluble protein level, decreased activity of AR, and lowered AOPP and AGEs levels. The results suggest that berberine administered orally positively affects the lenses of diabetic rats, and should be further examined with regard to its anticataract potential.

Intracellular betaine substitutes for sorbitol in protecting renal medullary cells from hypertonicity

1991 ◽  
Vol 260 (4) ◽  
pp. F494-F497 ◽  
Author(s):  
T. Moriyama ◽  
A. Garcia-Perez ◽  
A. D. Olson ◽  
M. B. Burg
Keyword(s):  
Aldose Reductase ◽  
Reductase Activity ◽  
Organic Osmolytes ◽  
Cloning Efficiency ◽  
Hypertonic Medium ◽  
Aldose Reductase Inhibitors ◽  
Reductase Inhibitors ◽  
Nacl Concentration ◽  
Medullary Cells

Renal medullary cells are normally exposed to a variably high extracellular NaCl concentration. They compensate by accumulating large amounts of organic osmolytes, including sorbitol and betaine. The sorbitol is synthesized from glucose, catalyzed by aldose reductase. Previously, inhibition of aldose reductase activity was noted to greatly reduce renal medullary cell survival and growth (measured by cloning efficiency) in tissue cultures of renal medullary cells in hypertonic medium. In contrast, inhibition of aldose reductase and renal medullary sorbitol accumulation is not associated with kidney damage in vivo. In the present experiments we find that addition of betaine to the medium, and its resultant uptake by the cells, largely replaces the decrease in sorbitol caused by aldose reductase inhibitors and restores the cloning efficiency. We presume that in vivo uptake of betaine by renal medullary cells similarly protects them from harm when aldose reductase inhibitors lower sorbitol. The results also demonstrate that one organic osmolyte can substitute for another in protecting cells from hypertonicity, consistent with the compatible osmolytes hypothesis.

scholarly journals Scopoletin Inhibits Rat Aldose Reductase Activity and Cataractogenesis in Galactose-Fed Rats

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Junghyun Kim ◽  
Chan-Sik Kim ◽  
Yun Mi Lee ◽  
Eunjin Sohn ◽  
Kyuhyung Jo ◽  
...  
Keyword(s):  
Aldose Reductase ◽  
Reductase Activity ◽  
Diabetic Patients ◽  
Membrane Rupture ◽  
Magnolia Fargesii ◽  
Sugar Cataract ◽  
Induced Changes ◽  
Rate Limiting ◽  
And Oxidative Stress

Cataracts are a major cause of human blindness. Aldose reductase (AR) is an important rate-limiting enzyme that contributes to cataract induction in diabetic patients. Scopoletin is the main bioactive constituent of flower buds fromMagnolia fargesiiand is known to inhibit AR activity. To assess scopoletin’s ability to mitigate sugar cataract formationin vivo, we studied its effects in a rat model of dietary galactose-induced sugar cataracts. Galactose-fed rats were orally dosed with scopoletin (10 or 50 mg/kg body weight) once a day for 2 weeks. Administering scopoletin delayed the progression of the cataracts that were induced by dietary galactose. Scopoletin also prevented galactose-induced changes in lens morphology, such as lens fiber swelling and membrane rupture. Scopoletin’s protective effect against sugar cataracts was mediated by inhibiting both AR activity and oxidative stress. These results suggest that scopoletin is a useful treatment for sugar cataracts.

Ancylostoma caninum Anticoagulant Peptide Blocks Metastasis In Vivo and Inhibits Factor Xa Binding to Melanoma Cells In Vitro

1998 ◽  
Vol 79 (05) ◽  
pp. 1041-1047 ◽  
Author(s):  
Kathleen M. Donnelly ◽  
Michael E. Bromberg ◽  
Aaron Milstone ◽  
Jennifer Madison McNiff ◽  
Gordon Terwilliger ◽  
...  
Keyword(s):  
Active Site ◽  
Thrombin Generation ◽  
Factor Xa ◽  
Coagulation Factor ◽  
Melanoma Cells ◽  
Factor V ◽  
Ancylostoma Caninum ◽  
Metastatic Activity

SummaryWe evaluated the in vivo anti-metastatic activity of recombinant Ancylostoma caninum Anticoagulant Peptide (rAcAP), a potent (Ki = 265 pM) and specific active site inhibitor of human coagulation factor Xa originally isolated from bloodfeeding hookworms. Subcutaneous injection of SCID mice with rAcAP (0.01-0.2 mg/mouse) prior to tail vein injection of LOX human melanoma cells resulted in a dose dependent reduction in pulmonary metastases. In order to elucidate potential mechanisms of rAcAP’s anti-metastatic activity, experiments were carried out to identify specific interactions between factor Xa and LOX. Binding of biotinylated factor Xa to LOX monolayers was both specific and saturable (Kd = 15 nM). Competition experiments using antibodies to previously identified factor Xa binding proteins, including factor V/Va, effector cell protease receptor-1, and tissue factor pathway inhibitor failed to implicate any of these molecules as significant binding sites for Factor Xa. Functional prothrombinase activity was also supported by LOX, with a half maximal rate of thrombin generation detected at a factor Xa concentration of 2.4 nM. Additional competition experiments using an excess of either rAcAP or active site blocked factor Xa (EGR-Xa) revealed that most of the total factor Xa binding to LOX is mediated via interaction with the enzyme’s active site, predicting that the vast majority of cell-associated factor Xa does not participate directly in thrombin generation. In addition to establishing two distinct mechanisms of factor Xa binding to melanoma, these data raise the possibility that rAcAP’s antimetastatic effect in vivo might involve novel non-coagulant pathways, perhaps via inhibition of active-site mediated interactions between factor Xa and tumor cells.

Turnover of Human Extrinsic (Tissue-Type) Plasminogen Activator in Rabbits

1981 ◽  
Vol 46 (03) ◽  
pp. 658-661 ◽  
Author(s):  
C Korninger ◽  
J M Stassen ◽  
D Collen
Keyword(s):  
Plasminogen Activator ◽  
Intravenous Injection ◽  
Active Site ◽  
Half Life ◽  
Degradation Products ◽  
Gel Filtration ◽  
Tissue Type ◽  
Organ Distribution ◽  
Small Rise

SummaryThe turnover of highly purified human extrinsic plasminogen activator (EPA) (one- and two-chain form) was studied in rabbits. Following intravenous injection, EPA-activity declined rapidly. The disappearance rate of EPA from the plasma could adequately be described by a single exponential term with a t ½ of approximately 2 min for both the one-chain and two-chain forms of EPA.The clearance and organ distribution of EPA was studied by using 125I-labeled preparations. Following intravenous injection of 125I-1abeled EPA the radioactivity disappeared rapidly from the plasma also with a t ½ of approximately 2 min down to a level of 15 to 20 percent, followed by a small rise of blood radioactivity. Gel filtration of serial samples revealed that the secondary increase of the radioactivity was due to the reappearance of radioactive breakdown products in the blood. Measurement of the organ distribution of 125I at different time intervals revealed that EPA was rapidly accumulated in the liver, followed by a release of degradation products in the blood.Experimental hepatectomy markedly prolonged the half-life of EPA in the blood. Blocking the active site histidine of EPA had no effect on the half-life of EPA in blood nor on the gel filtration patterns of 125I in serial plasma samples.It is concluded that human EPA is rapidly removed from the blood of rabbits by clearance and degradation in the liver. Recognition by the liver does not require a functional active site in the enzyme. Neutralization in plasma by protease inhibitors does not represent a significant pathway of EPA inactivation in vivo.

The Effect of Active Site-inhibited Factor VIIa on Tissue Factor-initiated Coagulation Using Platelets before and after Aspirin Administration

1997 ◽  
Vol 78 (04) ◽  
pp. 1202-1208 ◽  
Author(s):  
Marianne Kjalke ◽  
Julie A Oliver ◽  
Dougald M Monroe ◽  
Maureane Hoffman ◽  
Mirella Ezban ◽  
...  
Keyword(s):  
Tissue Factor ◽  
Active Site ◽  
Large Scale ◽  
Thrombin Generation ◽  
Factor Viia ◽  
Dependent Manner ◽  
Antithrombotic Agent ◽  
Before And After ◽  
Ic50 Values

SummaryActive site-inactivated factor VIIa has potential as an antithrombotic agent. The effects of D-Phe-L-Phe-L-Arg-chloromethyl ketone-treated factor VIla (FFR-FVIIa) were evaluated in a cell-based system mimicking in vivo initiation of coagulation. FFR-FVIIa inhibited platelet activation (as measured by expression of P-selectin) and subsequent large-scale thrombin generation in a dose-dependent manner with IC50 values of 1.4 ± 0.8 nM (n = 8) and 0.9 ± 0.7 nM (n = 7), respectively. Kd for factor VIIa binding to monocytes ki for FFR-FVIIa competing with factor VIIa were similar (11.4 ± 0.8 pM and 10.6 ± 1.1 pM, respectively), showing that FFR-FVIIa binds to tissue factor in the tenase complex with the same affinity as factor VIIa. Using platelets from volunteers before and after ingestion of aspirin (1.3 g), there were no significant differences in the IC50 values of FFR-FVIIa [after aspirin ingestion, the IC50 values were 1.7 ± 0.9 nM (n = 8) for P-selectin expression, p = 0.37, and 1.4 ± 1.3 nM (n = 7) for thrombin generation, p = 0.38]. This shows that aspirin treatment of platelets does not influence the inhibition of tissue factor-initiated coagulation by FFR-FVIIa, probably because thrombin activation of platelets is not entirely dependent upon expression of thromboxane A2.

Acyl-Enzymes as Thrombolytic Agents in a Rabbit Model of Venous Thrombosis

1982 ◽  
Vol 47 (03) ◽  
pp. 269-274 ◽  
Author(s):  
R A G Smith ◽  
R J Dupe ◽  
P D English ◽  
J Green
Keyword(s):  
Venous Thrombosis ◽  
Active Site ◽  
Fibrinolytic Activity ◽  
Rabbit Model ◽  
Fibrinolytic Agent ◽  
Essential Nature ◽  
Thrombolytic Agents

SummaryA derivative of human lys-plasmin in which the active site has been reversibly acylated (BRL 26920; p-anisoyl human lys-plasmin) has been examined as a fibrinolytic agent in a previously described rabbit model of venous thrombosis and shown to be significantly more active and less fibrinogenolytic than free plasmin. A p-anisoylated derivative of a streptokinase (SK)-activated plasmin preparation was significantly less fibrinogenolytic in vivo than the non-acylated enzyme. Acylation increased the fibrinolytic activity of preparations of SK-plasmin activator complexes. BRL 26921, the active site anisoylated derivative of the primary 2-chain SK-plasminogen complex was the most potent fibrinolytic agent studied. SK-Val442-plasminogen complexes, free or acylated, were biologically inactive in this model and confirm the essential nature of fibrin binding processes for effective thrombolysis in vivo.

Acyl-Enzymes as Thrombolytic Agents in Dog Models of Venous Thrombosis and Pulmonary Embolism

1984 ◽  
Vol 51 (02) ◽  
pp. 248-253 ◽  
Author(s):  
R J Dupe ◽  
P D English ◽  
R A G Smith ◽  
J Green
Keyword(s):  
Pulmonary Embolism ◽  
Side Effects ◽  
Venous Thrombosis ◽  
Active Site ◽  
Acute Pulmonary Embolism ◽  
Quantitative Model ◽  
Beagle Dog ◽  
Thrombosis Model ◽  
Derivatives Of

SummaryA quantitative model of venous thrombosis in the beagle dog is described. The model was adapted to permit ageing of isolated experimental clots in vivo. A model of acute pulmonary embolism in this species is also described. In the venous thrombosis model, infusion of streptokinase (SK) or SK-activated human plasmin gave significant lysis but bolus doses of SK. plasmin complex were ineffective. Active site anisoylated derivatives of SK. plasminogen complex, SK-activated plasmin and activator-free plasmin were all active when given as bolus doses in both models. At lytic doses, the acyl-enzymes caused fewer side-effects attributable to plasminaemia than the corresponding unmodified enzymes.

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